This section provides background information related to the present disclosure which is not necessarily prior art.
Different techniques have been used in various manufacturing processes, such as manufacturing in the automobile industry, to reduce the weight of a vehicle, while still maintaining its structural integrity. For example, tailor-rolled blanks are commonly used to form structural components for vehicles that need to fulfill specialized load requirements. A sheet metal panel or blank may be rolled to predetermined thicknesses and then roll formed or stamped by being pressed between a pair of dies to create a complex three-dimensional shaped component. The sheet metal material is chosen for its desirable characteristics, such as strength, ductility, and other properties related to the metal alloy. For example, the B-pillar structural component of a car body desirably exhibits a relatively high structural rigidity in the areas corresponding to the body of the occupant, while having increased deformability in the lower region at or below the occupant's seat to facilitate buckling of the B-pillar below seat level when force or impact is applied. As the structural component has different performance requirements in different regions, such a component can be made with multiple distinct pieces assembled together or from a single piece having different thicknesses.
Tailor rolled blanks can form such structural components having different thicknesses and therefore different mechanical properties along the panel or blank. Tailor rolled blanks have an advantage over alternatives like tailor-welded assemblies (where different pieces are welded together), in that they do not have welds or seams that can introduce potential weak regions or areas where corrosion could occur. Furthermore, many more transitions or stepped changes in thicknesses may be provided in a tailor rolled blank than a tailor-welded blank assembly, providing more design flexibility. By way of non-limiting example, tailor rolled blank assemblies may be used to form structural components in vehicles, for example, rocker rails, structural pillars (such as A-pillars, B-pillars, C-pillars, and/or D-pillars), hinge pillars, vehicle doors, roofs, hoods, trunk lids, engine rails, and other components with high strength requirements.
In a typical simplified process for forming tailor rolled blanks, a metal sheet or strip can undergo a rolling process that creates different thicknesses along the length of the sheet or strip. Prior to tailoring rolling, the metal sheet or strip material is cast, treated as necessary, cooled, and then rolled into an elongated sheet or strip having a uniform thickness, which then is rolled into a coil. Subsequently, the sheet material is uncoiled, typically at another processing facility, and subjected to a tailor blank rolling process. The sheet passes between one or more cold rolling stations, where different thicknesses may be produced along a length of the strip as it passes by rollers. However, in conventional processes, the thickness remains constant laterally or widthwise across the strip and only varies along a length of the strip. Any changes in thickness are formed in the sheet material lengthwise by changing and controlling a gap between rollers as the sheet material passes or rolls through. Such changes in the gap are typically achieved where the tailor rollers oscillated. Such systems require dynamic and precision control of the rollers to control the gap height and often cannot provide smooth, short transitions between distinct thicknesses. Furthermore, the dynamic control roller systems and processes are quite costly.
It would be desirable to develop alternative new methods for forming structural components that are required to exhibit variable properties in different regions, such as tailor rolled blanks, where such new processes provide superior control over thickness transitions, including an ability to tightly control thicknesses widthwise across a sheet or strip. Further, it would be desirable to form tailor rolled blanks via a process that is less expensive while having improved tailor rolled blank quality.